The current technology uses electrodes to measure electrical activity in a subject's biological tissue, e.g. muscles. Each electrode is either bare or individually covered with a conductive medium while the highest possible resistivity is maintained between the electrodes.
The use of an electrode array to measure electrical signals from, for example, a muscle requires that at least one signal electrode and a reference electrode be in contact with the subject's biological tissue via an electrically conducting medium to produce a defined muscle-related electric potential. If an electrode is in a poor electrically conducting medium, e.g. loses contact with the biological tissue and is isolated in air, it will deliver a non defined electric potential dominated by capacitive disturbances; the electrode will then act similar to an antenna. An electrically conducting medium can comprise any electrolyte or conductive substance/material. Such a non defined electric potential can still present an amplitude higher than the common noise level and can be mistakenly included in the signal processing as a valid signal representative of the electrical activity of the subject's muscle.
A poor electrically conducting medium or the absence of electrically conducting medium between one electrode of an array and the subject's biological tissue will cause a loss of the balancing “half-cell potential” and change the electrode potential relative to the electric potentials on the other electrodes of the array that have maintained contact with the biological tissue; more specifically, the DC potential will be altered. Also, the loss of contact of one electrode with the biological tissue increases the electrode impedance and also makes the electrode more sensitive to capacitively-induced disturbances. Consequently, the electric potentials on the various electrodes of the array will be different depending on whether these electrodes maintain or not contact with the subject's biological tissue. Accurate measurements require either removal of the DC component or removal of the channels with DC offset. Offset problems affect primarily the first amplification stage, which has to produce limited gain in case of large DC levels.
Recently, the feasibility of improving signal quality by covering an electrode array for measuring electrical activity in a subject's biological tissue with a mesh/matrix was demonstrated.
However, no method/technology is known or currently used to control the inter-electrode resistivity of an electrode array for the purpose of improving quality of the measured signals related to electrical activity of a subject's biological tissue. Control of the inter-electrode resistivity of an electrode array results in improvement of the signal quality by eliminating artifactual influences/disturbances due to poor electrode-to-tissue contact.